The present funded contract project maintains a bank of cryopreserved animal and human breast tumors with unique biological and endocrinological characteristics. In addition, antibodies to various types of collagens and procollagens, and antigens and antibodies to human and rat alpha-lactalbumin are maintained. Characterization studies are done on each tumor system prior to cryopreservation as well as on the third transplant generation post-freeze and thaw. Monitoring for contamination is done prior to cryopreservation and immediately following the thawing of the vials. Historical data and bibliography are documented on each tumor system. These tumors are available to scientists throughout the world upon written request and approval of the NCI Project Officer at no cost except for shipping. The Bank also maintains in cryopreservation seed samples of certain human and animal, normal and malignant, mammary cell culture lines, all of these well characterized in previous studies for safe storage only and not for distribution.